Leafy and weedy seadragon genomes connect genic and repetitive DNA features to the extravagant biology of Syngnathid fishes

September 05, 2021

Clayton M. Small (1,2), Hope M. Healey (1), Mark C. Currey (1), Emily A. Beck (1,2), Julian Catchen (3), Angela S. P. Lin (4), William A. Cresko (1,2), Susan Bassham (1)
bioRxiv, September 2021. DOI: 10.1101/2021.09.24.461757


genome sequencing; novel traits; evolution; miRNA; transposable elements; molecular evolution; fibroblast growth factors; syngnathids


Seadragons are a remarkable lineage of teleost fishes, and they are members of the family Syngnathidae renowned for having evolved male pregnancy. Comprising three known species, seadragons are widely recognized and admired for their fantastical body forms and coloration, and their specific habitat requirements have made them flagship representatives for marine conservation and natural history interests. Until recently, a gap has been the lack of significant genomic resources for seadragons. We have produced gene-annotated, chromosome-scale genome models for the leafy and weedy seadragon to advance investigations into evolutionary innovation and elaboration of morphological traits in seadragons as well as their pipefish and seahorse relatives. We identified several interesting features specific to seadragon genomes, including divergent non-coding regions near a developmental gene important for integumentary outgrowth, a high genome-wide density of repetitive DNA, and recent expansions of transposable elements and a vesicular trafficking gene family. Surprisingly, comparative analyses leveraging the seadragon genomes and additional syngnathid and outgroup genomes revealed striking, syngnathid-specific losses in the family of fibroblast growth factors (FGFs), which likely involve re-organization of highly conserved gene regulatory networks in ways that have not previously been documented in natural populations. The resources presented here serve as important tools for future evolutionary studies of developmental processes in syngnathids and will be a key resource for conservation studies of the extravagant seadragons and their relatives.

How Our Software Was Used

Dragonfly was used for the 3D reconstruction of X-ray data.

Author Affiliation

(1) Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403.
(2) Presidential Initiative in Data Science, University of Oregon, Eugene, OR 97403.
(3) Department of Evolution, Ecology and Behavior, University of Illinois at Urbana-Champaign, Urbana, IL 61801 .
(4) Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR 97403.